N,n-di-lower alkyl-2-naphthamide as an algaecide



United States Patent Office 3,481,730 Patented Dec. 2, 1969 3,481,730N,N-DI-LOWER ALKYL-Z-NAPHTHAMIDE AS 1 AN ALGAECIDE John D. Douros, Jr.,Fanwo'od, N.J., and William D. Vanderwerlf, Wilmington, Del., assignorsto Sun Oil Fompany, Philadelphia, Pa., a corporation of New .ersey NoDrawing. Original application Oct. 7, 1963, Ser. No. 314,537, now PatentNo. 3,305,583, dated Feb. 21, 1967. Divided and this application May 6,1966, Ser.

Int. Cl. A01n 9/20 US. Cl. 71-67 8 Claims ABSTRACT OF THE DISCLOSUREThis invention relates to a method killing chlorophyllcontaining algaewith N,N-di-lower alkyl-2-naphthamides.

This is a division of application Ser. No. 314,537, filed Oct. 7, 1963,now US. Patent 3,305,583.

This invention relates to certain novel naphthalene amides and to theiruse as materials for killing algae. More particularly, this inventionrelates to the use of N,N-di-lower alkyl-2-naphthamides for killingchlorophyll-containing algae, and to methods of preparing thesecompounds.

The presence of algae in water generally results in such deleteriouseffects as rampant plant growth in large bodies of water, discoloration,bad taste and odor of water in streams, pools and the like, as well asblockage of pipes, filters, tanks and similar industrial apparatus.Since the volume of water to be treated is usually quite large, it isessential that highly effective yet low cost algaecides be found tocontrol such growth. By highly effective is meant compounds which willkill algae at sufficiently low concentrations that the algaecide itselfwill not affect the quality or usefulness of the water to be so treated,nor the aquatic life contained therein, particularly fish.

It has now been found that these and other desiderata To each flask wasthen added a known amount of N,N- diethyl-Z-naphthamide, the amountbeing indicated in Table I as micrograms per ml. of solution. Since mostof the solution is water, the stated amounts are essentially equivalentto parts per million parts of solution. For comparative purposes fourmore samples were prepared in the same manner as above except that noN,N-diethyl- Z-naphthamide was added. Similarly, as an additionalcontrol, corresponding samples were prepared to which just ethanol wasadded.

The extent to which the algae were killed was determined eight dayslater by visual observation of the color and turbidity of the solutionsin each flask and comparison with the untreated control flasks.Initially each solution had the color characteristic of the algaepresent therein. As the algae were killed, the color disappeared due tothe decrease in chlorophyll production by the algae. When all the algaewere killed, the solution was colorless. Similarly, as the algae werekilled, the solutions became less turbid; when all the algae were killedthe solution was clear.

The results of the above tests were as follows:

TABLE I Concentration Scenedesmus Chlorella Oscillatoria Coccohlorisg/ml. iquus vulgaris bomcii elabens 1007 3% ethanol was used only in theease of the highest concentration of compound.

inhibition TABLE II Scenedesmus Chlorellu Anabena OscillatoriaC'occochloris Synurs obliquus vulqarz's C'atenula borneti (10671.8 8]).

Concentration [lg/ml;

++++ No inhibition. 25% inhibition. inhibition. 75% inhibition. 100%inhibition.

may be achieved by the use of such N,N-di-lower alkylnaphthamides asN,N-dimethyl-Z-naphthamide, N,N-diethyl-2-naphthamide and the like inconcentrations as low as 10 parts per million of water.

The effectiveness of N,N-diethyl-Z-naphthamide as an algaecide wasdetermined by the following tests:

Four different algae cultures were each placed in a separate flaskcontaining a dilute aqueous sugar solution as the nutrient. Ethylalcohol was then added to the flask containing 100 ,ug./ml. ofnaphthamide in an amount suflicient to give an ethyl alcoholconcentration of 3% by volume. The purpose of the alcohol was to insurerapid and complete solution of the higher concentration ofN,N-diethyl-Z-naphthamide. The algae concentration in each flask wasapproximately 10 cells per ml. of solution, including both nutrient andalcohol. The various species of algae present as indicated in Table Ibelow are representative of the major classes of algae.

It will seen from the above data that N,N-diethyl-2- naphthamide givesup to protection against a wide range of algae in concentrations of fromabout 10-100 p.p.m. The amount of N,N-di-lower alkyl-2-naphthamide addedto the water will vary depending upon such factors as the type of algaepresent, the nature of the body of water, i.e. flowing stream vs. smalllake etc., and the inherent ability of the body of water to supportalgae growth. This inherent ability in turn depends upon such factors asexposure to sunlight, salinity, pH and the like. While in most cases theconcentration of naphthamide required to kill or inhibit the growth ofall algae will vary from 10-100 p.p.m., the preferred amount is in therange of 30-100 p.p.m.

The N,N-di-lower aIkyI-Z-naphthamides can be added to the wateraccording to conventional techniques for algaecide application. Whentreating a lake or other body of water which is relatively calm, theconventional proce- 3 dure is to spray an aqueous solution of thealgaecide over the surface of the water. For algaecides not readilysoluable in water the algaecide is normally pre-dissolved in awater-miscible solvent. In the case of the instant naphthamides, eitherwater or ethanol may be 'used, while in the case of moving water, suchas that in a water-treating plant, the algaecide can be added to thewater in small amounts at periodic intervals.

The N,N-di-lower alkyl-2-naphthamides, subject of the present invention,are conveniently prepared by reacting a naphthoyl halide, as for examplenaphthoyl chloride, with a di-lower alkylamine in a suitable organicsolvent such as ether, acetone or the like at reflux temperatures, andrecovering the corresponding N,N-di-lower alkyl-2- naphthamide byconventional means. Typical examples of methods of preparing thealgaecides of the invention are illustrated below:

EXAMPLE I N,N-dimethyl-2-naphtharnide A solution of 190 grams of2-naphthoyl chloride in 500 ml. of ether is added slowly to a stirredsolution of 250 ml. of dimethylamine in 500 ml. of ether in a twoliterflask fitted with a reflux condenser. The mixture is stirred for onehour after all of the naphthoyl chloride has been added. The ethersolution is then washed first with dilute NaOH, again with water, driedover anhydrous Na SO and the ether stripped oil to yield N,N-dimethyl-Z-naphthamide.

In accordance with the foregoing procedure, but substitutingdipropylamine for dimethylamine, there is obtained the correspondingN,N-dipropyl-Z-naphthamide.

EXAMPLE II N,N-diethyl-Z-naphthamide A solution of 190 grams of2-naphthoyl chloride in 500 ml. of ether is added slowly to a stirredsolution of 250 ml. of diethylamine in 500 of ether in a two-liter flaskfilled with a reflux condenser. The mixture is stirred for one hourafter all of the naphthoyl chloride has been added. The ether solutionis then washed first with water, then with dilute NaOH, again withwater, dried over anhydrous Na SO and the ether stripped off. Theproduct obtained is a slightly yellowish oil which may be distilledunder vacuum if desired to yield N,N-diethyl-Z-naphthamide.

In accordance with the foregoing procedure, but sub- 4 stitutingdibutylamine, for diethylamine, there is obtained the correspondingN,N-dibutyl-Z-naphthamide.

The invention claimed is:

1. A method of killing chlorophyll-containing algae Which comprisesapplying an elfective algaecidal amount of an N,N-di-loweralkyl-Z-naphthamide to chlorophyllcontaining algae.

2. The method according to claim 1 wherein the algaecide isN,N-dimethyl-2-naphthamide.

3. The method according to claim 1 wherein the algaecide isN,N-diethyl-Z-naphthamide.

4. A method of killing chlorophyll-containing algae in water whichcomprises adding an effective algaecidal amount of an N,N-di-loweralkyl-Z-naphthamide to the water.

5. The method according to claim 4 wherein the amount of saidN,N-di-lower alkyl-2-naphthamide is in the range of 10-100 parts permillion parts of water.

6. The method according to claim 4 wherein the amount of saidN,N-di-lower alkyl-Z-naphthamide is in the range of 30-100 parts permillion parts of water.

7. The method according to claim 4 wherein said algae are selected fromthe genera consisting of Scenedesmus, Chlorella, Anabena, Oscillatoria,Coccochloris and Synura.

8. A method of killing chlorophyll-containing algae selected from thegenera consisting of Scenedesmus, Chlorella, Anabena, Oscillatoria,Coccochloris and Synura which comprises adding to water containing saidalgae from 30-100 parts per million parts of Water ofN,N-diethyl-Z-naphthamide.

References Cited UNITED STATES PATENTS 2,904,465 9/1959 Moorefield167-32 3,035,969 5/1962 Hartle l6732 3,252,855 5/1966 Fairfield 167l3OTHER REFERENCES Alexander et al.: Journal of Org. Chem., vol. 25, pp.626-632 (1960).

Higuchi et al.: Anal. Chem, v01. 34, pp. 400-403 (March 1962).

ALBERT T. MEYERS, Primary Examiner JEROME D. GOLDBERG, AssistantExaminer

